Celecoxib (4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide) is a substituted pyrazolylbenzenesulfonamide represented by the structure (I):

Celecoxib belongs to the general class of non-steroidal anti-inflammatory drugs (NSAIDs). Unlike traditional NSAIDs, celecoxib is a selective inhibitor of cyclooxygenase II (COX-2) that causes fewer side effects when administered to a subject. The synthesis and use of celecoxib are further described in U.S. Pat. Nos. 5,466,823, 5,510,496, 5,563,165, 5,753,688, 5,760,068, 5,972,986, 6,156,781, and 6,579,895, the contents of which are incorporated by reference in their entireties. Orally deliverable liquid formulations of celecoxib are discussed in U.S. Patent Application Publication No. 2002/0107250, the contents of which are incorporated herein by reference in their entirety.
Other COX-2 inhibitory drugs are related to celecoxib, which form part of a larger group of drugs, all of which are benzene sulfonamides. These include: deracoxib, which is 4-[3-fluoro-4-methoxyphenyl)-3-difluoromethyl-1H-pyrazol-1-yl]benzene sulfonamide; valdecoxib, which is 4-[5-methyl-3-phenyl isoxazol-4-yl]benzene sulfonamide; rofecoxib, which is 3-phenyl-4-[-(methylsulfonyl)phenyl]-5H-furan-2-one; and etoricoxib, which is 5-chloro-3-(4-methylsulfonyl)phenyl-2-(2-methyl-5-pyridinyl)pyridine. These drugs are described in further detail in WO 01/78724 and WO 02/102376.
In its commercially available form, trademarked as CELEBREX, celecoxib is a neutral molecule that is essentially insoluble in water. Celecoxib typically exists as needle-like crystals, which tend to aggregate into a mass. Aggregation occurs even when celecoxib is mixed with other substances, such that a non-uniform mixture is obtained. These properties are shared by other pyrazolylbenzenesulfonamides and present significant problems in preparing pharmaceutical formulations of the drugs, particularly oral formulations.
It would be advantageous to provide new forms of drugs that have low aqueous dissolution which have improved properties, in particular as oral formulations. In particular, even where an active pharmaceutical ingredient (API) of low aqueous solubility is provided in a form which has improved aqueous solubility, there still exists a problem when dissolution of the API is required, for example after having been taken as an oral formulation where the API becomes diluted in the alimentary canal. (The terms “API” and “pharmaceutical” are used herein interchangeably.) In this situation, APIs having low aqueous solubility tend to come out of solution. When this happens, for example by a process of crystallization or precipitation, the bioavailability of the API is significantly decreased. It would therefore be desirable to improve the properties of formulations containing such APIs so as to increase the bioavailability of the API in an orally-administered form, thereby providing a more rapid onset to therapeutic effect.